BMR question fat person vs lean muscle at the same weight.

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rsclause
rsclause Posts: 3,103 Member
in Health and Weight Loss
My wife and I were arguing about this so I thought I would post it here.

Lets suppose you have two females that are the same age, height, weight but one is sedentary and the other has been active with little fat just lean muscle. Now they both go on vacation and just sit in the sun together drinking margaritas and eating burgers and fries.

Question #1: At the same new activity level do they have the same BMR?
Question #2: With equal calorie intake/activity level would they gain the same amount of weight?

Obviously different people will possibly metabolize food differently and have other differences but I think they will have the same BMR and gain roughly the same weight. She says the lean muscle candidate will have a higher BMR and gain less.

Replies

  • hlnebel
    hlnebel Posts: 71 Member
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    My understanding is that BMR doesn't include any activity, so since the two people in your example have different body fat %, their BMR is different and will always be different.
  • rsclause
    rsclause Posts: 3,103 Member
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    hlnebel wrote: »
    My understanding is that BMR doesn't include any activity, so since the two people in your example have different body fat %, their BMR is different and will always be different.

    So with similar weight, age etc. BMR is determined by body fat % alone? I have alway heard "muscle burns more calories than fat" but I always assumed that it was the building or maintaining of the muscle was the reason. In this example they were both being couch potatoes so even if not relevant it is the same. Thanks for the reply.
  • rsclause
    rsclause Posts: 3,103 Member
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    Okay I just looked up the formula for BMR and it looks to involve height weight & age. I guess the other problem is that it is so unlikely to have two identical people of the same weight and have one fat, one lean muscle. But it had me wondering.
  • Yi5hedr3
    Yi5hedr3 Posts: 2,696 Member
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    If muscle mass (LBW) is different, and bodyweight is same, the one with more muscle will have higher BMR.
  • Francl27
    Francl27 Posts: 26,372 Member
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    1 pound of muscle will burn about 4 more calories a day or something.
  • aub6689
    aub6689 Posts: 351 Member
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    Most likely the one with more muscle is going to have a higher BMR. This is why bodybuilders are sometimes eating over 5000 calories, it isn't merely to gain mass, but also because their current muscle mass gives them a high BMR. This is also one reason why there is a different formula to calculate BMR for men, because men generally have more muscle mass.
  • mburgess458
    mburgess458 Posts: 480 Member
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    Most BMR estimate calculations don't take into account bodyfat percentage (because that can be tough to know), but some definitely do. For example, the Katch-McArdle Forumla includes body fat percentage as an input. http://www.calculatorpro.com/calculator/katch-mcardle-bmr-calculator/

    Your BMR isn't determined simply by your height and weight. A lb of muscle burns more calories than a lb of fat. Period. Even if that muscle is just sitting by the pool it requires more energy than fat cells.
  • cwolfman13
    cwolfman13 Posts: 41,874 Member
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    The one with more muscle will have a higher BMR...
  • blues4miles
    blues4miles Posts: 1,481 Member
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    Learned some new stuff myself, interesting discussion.
  • daisygirl2017
    daisygirl2017 Posts: 107 Member
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    So why aren't we eating more according to body fat %? Because if two girls same height, weight, etc the general BMR calculator would have them eating same amount of calories but one will lose weight faster than other.
  • lemurcat12
    lemurcat12 Posts: 30,886 Member
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    mrzpeep391 wrote: »
    So why aren't we eating more according to body fat %? Because if two girls same height, weight, etc the general BMR calculator would have them eating same amount of calories but one will lose weight faster than other.

    There is a BF based calculator which is the best one (Katch McArdle) but most people don't know their BF % at all accurately.
  • rankinsect
    rankinsect Posts: 2,238 Member
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    mrzpeep391 wrote: »
    So why aren't we eating more according to body fat %? Because if two girls same height, weight, etc the general BMR calculator would have them eating same amount of calories but one will lose weight faster than other.

    Because all "calories out" are estimates, and in most cases this estimate is good enough. Unless you have a device strapped to your face 24/7 measuring oxygen consumption, everything is an estimate. Most people don't have an accurate measurement of body fat, so it's not really more accurate to use that when you're inaccurate with your inputs. For that matter even the calories you eat are estimates of varying degrees of accuracy, even if you weigh to the gram. All that really matters in either case are that the estimates are close enough to get you close to the deficit you want.

    That's why the real proof is in the progress. You can estimate your BMR or TDEE, you can plan for a theoretical deficit, but the proof is in the weight you lose, and by looking at your loss over time, you can fine tune your calories consumed.
  • Larissa_NY
    Larissa_NY Posts: 495 Member
    edited May 2016
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    rankinsect wrote: »
    mrzpeep391 wrote: »
    So why aren't we eating more according to body fat %? Because if two girls same height, weight, etc the general BMR calculator would have them eating same amount of calories but one will lose weight faster than other.

    Because all "calories out" are estimates, and in most cases this estimate is good enough. Unless you have a device strapped to your face 24/7 measuring oxygen consumption, everything is an estimate. Most people don't have an accurate measurement of body fat, so it's not really more accurate to use that when you're inaccurate with your inputs. For that matter even the calories you eat are estimates of varying degrees of accuracy, even if you weigh to the gram. All that really matters in either case are that the estimates are close enough to get you close to the deficit you want.

    That's why the real proof is in the progress. You can estimate your BMR or TDEE, you can plan for a theoretical deficit, but the proof is in the weight you lose, and by looking at your loss over time, you can fine tune your calories consumed.

    This, but also two other things.

    First, the difference in BMR between two girls who need to lose weight, where one has more muscle than the other, is going to be pretty minimal. Sure, you can maybe eat one more strawberry a day, but at the level of the normal sedentary overweight person it's not a difference that will do you any good. If you're a professional athlete carrying around a ton of muscle, sure, the difference might be significant; but if you're a professional athlete, you're not likely to be looking to MFP to tell you how to lose twenty pounds.

    Second, the problem with approaches like MFP's is that it encourages people to view calories like a video game - as if the goal were to maximize the amount of food you can eat while still making the numbers come out right. Figuring out how to maximize the amount of food you eat is what made you overweight in the first place. If the goal of your weight loss is to eat as much as is humanly possible while still watching the scale go down, as soon as you stop watching the scale your weight is going to start coming back on. Unless you are actually trying to recover from anorexia, the goal of calorie counting is not "The person who eats the most food wins." The goal is to get to a normal-range weight in a healthy manner.
  • nosebag1212
    nosebag1212 Posts: 621 Member
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    lemurcat12 wrote: »
    mrzpeep391 wrote: »
    So why aren't we eating more according to body fat %? Because if two girls same height, weight, etc the general BMR calculator would have them eating same amount of calories but one will lose weight faster than other.

    There is a BF based calculator which is the best one (Katch McArdle) but most people don't know their BF % at all accurately.

    doesn't katch mccardle ONLY take into account lean bodymass though? surely this is a bad formula for overweight people as they have a lot of fat which the caculator ignores
  • yarwell
    yarwell Posts: 10,477 Member
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    nosebag1212 wrote: »
    lemurcat12 wrote: »
    mrzpeep391 wrote: »
    So why aren't we eating more according to body fat %? Because if two girls same height, weight, etc the general BMR calculator would have them eating same amount of calories but one will lose weight faster than other.

    There is a BF based calculator which is the best one (Katch McArdle) but most people don't know their BF % at all accurately.

    doesn't katch mccardle ONLY take into account lean bodymass though? surely this is a bad formula for overweight people as they have a lot of fat which the caculator ignores

    Depends how many calories per day you think fat tissue uses up I guess.

    K-M is less deceived by those >200 lbs than some other equations, but they're all regression on datasets so the key is to make sure that the subject is well represented by the dataset. Which may mean hopping back to the thirties, becoming a scrawny male and being conscripted into Mussolini's army ;-)

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